1. Field of the Invention
This invention relates to an overspeed protection (OSP) apparatus for an aeroplane gas turbine engine.
2. Description of the Related Art
In an overspeed protection apparatus for a gas turbine engine, a fuel supply line of the engine is interposed with a fuel shutoff valve (SOV) for shutting off or blocking the fuel supply to an engine combustion chamber when a detected turbine rotational speed exceeds a predetermined speed to stop combustion, thereby preventing overspeed of the engine turbine.
Specifically, an overspeed protection apparatus taught by Japanese Laid-Open Patent Application No. 2006-316773 is configured to have four CPUs that monitor the turbine rotational speed and, when two or more CPUs determine that the turbine rotational speed exceeds a predetermined speed, they discriminate that the engine is under overspeed condition and operate the shutoff valve to shut off the fuel supply to the combustion chamber. The configuration thus improves the reliability of the apparatus.